How Moisture Causes Mold And Musty Odors

That familiar musty odor in your basement - is that mold?

The musty odor in a basement is a very familiar and annoying problem that can have a negative effect on almost any home. In 90 percent of homes, the musty odor typically gets ignored, but it can have a negative impact on the health of occupants and diminish property value, as mold or the mere smell of it is enough to chase off potential buyers.

That musty odor is a simple mold that can grow in the very air we breathe, which can flourish under the right conditions. Molds are very simple organisms that can flourish in many different environments. The conditions required for mold to grow quickly include a food source combined with a moisture source and a stable or still environment. Mold spore is readily available in the air we breathe and the organic matter that is in a typical household environment makes for an excellent source to feed the mold.

We always recommend going after the moisture source when addressing any type of mold problem in a home. In the case of a typical basement, there are several sources of moisture to look for that can be the source for colonized mold, such as water seepage via pressure following heavy rains, condensation or plumbing leaks. Also, high relative humidity is another major source that typically gets ignored.

It is vital to make sure there are no plumbing leaks or condensation leaks, and if basement walls are leaking via cracks, it is important to address this by consulting an expert. These moisture sources are usually obvious because the evidence can be seen in the form of standing water, stained block walls or wet carpet, etc. If there is no water via pressure or condensation from ducts or pipes, that leaves only high relative humidity as a likely moisture source, which is typically a seasonal issue, as during the winter months, the heat from HVAC system will keep the relative humidity low.

Generally speaking, the ideal breathing environment is 35 percent to 45 percent. Greater than 60 percent is needed to support mold growth. During the spring, summer and fall months, the relative humidity can be consistently well above 60 percent in this region, and the AC system can add to high humidity by adding moist, humid air to the indoor environment.

The basement is the lowest part of the structure, and the heavy, humid air tends to fall to the lowest point and then becomes trapped in the basement space. Once the high relative humidity reaches a threshold of 60 percent or greater, combined with a stable air environment for 48 hours or longer, mold will colonize to elevated levels, which can create the familiar musty odor.

It is always better to go after moisture source, but it is often the case that during summer months, it is hard to keep relative humidity below 60 percent consistently. By actively moving the air with a circulation feature on the HVAC thermostat or fans on timers to run for 15 minutes every four to six hours, we can deny mold one of the ingredients necessary to colonize - a stable environment. A dehumidifier will work to help reduce humidity, but there are times of the year when it is very hard if not impossible for the dehumidifier to be effective because humidity is so high.

The key with relative humidity is that it is an invisible moisture source, and since it cannot be seen, the mold grows unnoticed until it’s too late, leaving the occupants with the musty odor. The musty odor is, of course, a high particle count that can not only have a negative effect on indoor air quality but also slowly deteriorate the basement finished space or stored items such as clothes, laundry, etc. This is often a problem that gets ignored because it may affect only one person in the home. But once molds build up, they don’t leave, and if concentrations are high enough, everyone will be bothered. Molds can linger for long periods of time and go dormant in times of drought, such as winter, only to flourish when the moisture source returns in the spring. If monitors are in place with a good dehumidifier and active ventilation, the basement should feel no different today or 20 years from today, but it is something to address early.

If you feel there is a problem in the home, call a mold expert at Action Waterproofing to inspect and offer information on how to treat the area of concern. Action Waterproofing can be reached by calling 877-729-7001.